Salamencetrainer34, It's a hilarious game that someone made up. You either takes cards from several packs or just random cards and play a sort of game with it.
It'd be hard to explain fully here, but basically you deal out the cards evenly among everyone, assign rules to how each card works, and then use each Pokemon's attacks (you don't need the energy). When something is knocked out, you take the next card from your pile and flip it face up to begin attacking. It's hilariously fun but some of the cards are really overpowered based on the rules we give them (like Magnezone can attack twice because of its ability, letting it do 160 damage in one turn).